Refs #18089; added a branch with work in progress on integration with zc.async to achieve async based import of content

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs@20723 a0171fae-0946-0410-966d-b1775066cd26
Refs #18089 Naaya; reverse the previous commit for the trunk, it was done by mistake

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs@20724 a0171fae-0946-0410-966d-b1775066cd26